1. Field of the Invention
The present invention generally relates to event recorders for vehicles and, more particularly, to a solid state event recorder which collects desired vehicle data, records the data in solid state memory over a period of time, and provides multiple options for transferring data from the recorder for playback and analysis. The subject invention has particular application in railroad locomotives, but the principles of the invention could be applied to other environments including aircraft and rubber tired road vehicles.
2. Description of the Prior Art
Event recorders for vehicles are well known in the art. These include recorders on trucks commonly required in the European Community states and recorders in airliner cockpits and in railroad locomotives. Such recorders are typically used to enforce regulations, monitor the operation of the vehicle, and to analyze events leading up to an accident in order to determine the cause of the accident.
One such event recorder used in the railroad industry is the Pulse Magnetic Tape Recorder (MTR) manufactured by Pulse Electronics, Inc. of Rockville, Md. This recorder was introduced in 1977 and significantly advanced the state-of-the-art in locomotive event recorders. Prior to the introduction of the Pulse MTR, railroads were using mechanical paper chart recorders that were unreliable, difficult to maintain and recorded very limited information. The Pulse MTR significantly reduced the number of moving parts, providing a more reliable recorder that was both affordable and easy to maintain.
Since the introduction of the first MTR, Pulse has continued to increase the capability of the locomotive event recorder system, introducing playback systems to support the on-board recorders. In addition, numerous sensor products have been introduced. Further, the MTR itself advanced from recording only speed, time and distance to the current multi-channel recorder which has become the industry standard.
The Pulse MTR uses a magnetic tape cartridge, similar to the audio tape cartridges. Four tracks of event data are recorded on the endless loop of magnetic tape. In order to obtain the greatest amount of data, the recorder drives the tape at very low speed, but data is overwritten as the tape loop cycles through the recorder. Thus, even at the low tape speed, the data recorded represents a relatively short time period, and because of the low tape speed, the resolution of the data recorded is limited.
To retrieve the data from the MTR, the magnetic tape must be removed from the recorder and taken to a playback station. When thousands of tapes are being extracted from locomotives each month, this represents a significant task. A less labor intensive method of retrieving this data would offer significant productivity advantages to the industry.
For these and other reasons, it is desirable to design a new generation of event recorders for railroad and other applications. These recorders should have a larger capacity for storing higher resolution data over a longer period of time, yet retain the ruggedness and reliability required for such applications. However, due to the large installed base of data playback and analysis equipment, any new event recorder should be compatible with that equipment.